raise指令触发异常实例

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

type
  epasswordinvalid = class(exception);

procedure TForm1.Button1Click(Sender: TObject);
var
  gpassword: string;
begin
  if edit1.Text <> edit2.Text then
    begin
      raise epasswordinvalid.Create('由程序员显示异常信息' + #10 + #13 + '密码输入有误！');
      edit2.Text := '';                         //此行永远不会被执行
    end
  else
    begin
      gpassword := edit1.Text;
      showmessage('密码设定完成');
    end;
  showmessage('欢迎光临！');                    //前面不产生异常时，此行才会执行
end;

end.